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Check valve principleRelease Date: January 01, 1754
Common faults of check valves and their solutions Common faults of check valves:
① The valve disc is broken; ② The medium flows backward.
The cause of the valve disc shattering is:
Wafer-type soft-seal butterfly valve is in a state of near-balanced pressure and “pulled sawing” each other. The valve flap is often beaten with the valve seat. The valve disc made of some brittle materials (such as cast iron and brass) is broken .
The preventive method is to adopt flange butterfly valve whose valve disc is tough material.
The reasons for media backflow are:
① The sealing surface is damaged; ② Impurities are trapped. Repairing sealing surfaces and cleaning impurities prevents backflow.
The check valve only allows the medium to flow in one direction and prevents it from flowing. Usually this kind of valve works automatically. Under the action of fluid pressure flowing in one direction, the valve disc opens; when the fluid flows in the opposite direction, the pressure of the fluid and the self-reclosing valve disc of the valve disc act on the valve seat to cut off the flow.
The check valve includes a swing check valve and a lift check valve. The swing check valve has a hinge mechanism, and a flap like a door rests freely on the inclined seat surface. In order to ensure that the valve disc can reach the appropriate position on the valve seat surface every time, the valve disc is designed in a hinge mechanism so that the valve disc has enough swing space and the valve disc is truly and comprehensively in contact with the valve seat. The discs can be made entirely of metal, or they can be inlaid with leather, rubber, or a synthetic covering, depending on the performance requirements. Swing check valve is fully open, the fluid pressure is almost unhindered, so the pressure drop across the valve is relatively small.
The disc of the butt-welded metal hard-seal butterfly valve is seated on the valve seat sealing surface on the valve body. Except that the valve disc can be lifted and lowered freely, the rest is like a stop valve. The fluid pressure causes the valve disc to lift from the sealing surface of the valve seat, and the backflow of the medium causes the valve disc to fall to the valve seat and cut off the flow. Depending on the conditions of use, the disc can be an all-metal structure, or it can be in the form of a rubber pad or rubber ring inlaid on the disc frame. Like the shut-off valve, the passage of fluid through the lifting check valve is also narrow, so the pressure drop through the lifting check valve is larger than that of the swing check valve, and the flow of the swing check valve is limited Rarely.